The invention pertains to the field of locating and chucking crankshaft workpieces within crankshaft machine tools.
In the manufacture of internal combustion engine crankshafts the crankshaft is formed by casting or forging to define the main and crank bearings, counterweights and other components of the crankshaft. The rough castings or forgings are then usually preliminarily machined to roughly size the bearings and to define chucking surfaces, or location surfaces, and then placed in a crankshaft lathe wherein the bearing surfaces are turned. After the lathe work, the crankshafts are usually transferred to finish grinding machines, and the bearing surfaces are ground, and sometimes burnished, to produce the final bearing finish.
Internal combustion engine crankshafts must be accurately machined, and heretofore one of the difficult problems encountered in crankshaft machine tools, particularly those of an automatic, or semi-automatic operation, lies in the accurate axial locating of the crankshaft workpiece in the machine tool chucks and subsequent securement when machining forces are applied. Of course, the positioning of the workpiece within the chucks will determine the axial location of the cutting operations occurring on the workpiece, and previous systems for axially locating and securing the crankshaft workpiece in the chucks often permitted inaccuracies resulting in the scrapping of the workpiece producing expensive material and time losses.